In U.S. Pat. No. 5,796,821 to Crouch et al, a hearing aid telephone interconnection system is described to enable hearing-impaired persons to use conventional telephone instruments. The system employs a T-coupler that is formed of an elongate coil of some 360 turns of 40-gauge magnet wire. The T-coupler has an arcuate shape that corresponds generally to a user's ear and of a conventional behind-the-ear hearing aid so that the body portion of the T-coupler can inductively couple audio signals into a T-coil of the hearing aid. The T-coupler is connected through an adapter box to the telephone cable leading also to a hand set. The T-coupler connection is by way of an audio plug, which, when inserted, causes an interruption of signals to the handset speaker.
A variety of U.S. patents can be found in which different techniques are used to couple a telephone to a hearing aid. One such patent, U.S. Pat. No. 5,086,464, to Groppe, describes a complex head set to couple the telephone speaker sound to the ear. In U.S. Pat. No. 3,396,245 a device is employed to automatically switch signals between a hearing aid and a telephone in two modes of operation.
Many of the more that 60 million people with hearing disabilities in the U.S. alone are presently unable to use standard telephone instruments that are in common use by persons having normal hearing ability. It is estimated that there is a population of 600 million people with hearing disabilities worldwide with an accelerating 15% annual growth rate in the United States alone.
Hearing impaired people on the whole do not have access to technology for enabling access to, or the capability of using and hearing on a telephone. There is a lack anything on the market that can fully address all issues that the hearing impaired face when it comes to doing just one task, namely of allowing them to just pick up a telephone and hear on it. While there are many devices on the market that claim that they allow the hearing impaired to do just that, upon closer inspection definite drawbacks manifest themselves in prior art devices.
For the better part of 40 years, the most often used technique is to use a large open-air coil to transmit an audio signal, via electromagnetic induction. These coils are commonly large, bulky and cumbersome to use and wear. While they have different shapes and forms, they tend to be worn either around the neck or as a fixture that hangs on the ear and thus tends to look out of place.
A number of TTY products (telecommunication devices for the deaf) are available in the market place. These products are typically terminals that transmit typed messages over telephone lines to a compatible terminal or to relay operators at the receiving end of the line, These TTY terminals are disadvantageous in that they do not meet the full accessibility needs of hearing impaired persons. According to the Tele-Consumer Hotline, less than one-half million people with hearing loss utilize a TTY for telecommunications due to the desire for voice telecommunications. It should also be pointed out that this technology is over 50 years old.
Sound amplification products also exist in the prior art, but they clearly do not amplify or transmit to the extent required to truly benefit a hearing disabled person. The 18-30 decibels of amplification typically realized from these prior art products will not truly benefit a person suffering from even a moderate hearing loss, let alone one who is severely to profoundly deaf.
Use of standard telephones with a volume control, a dual volume control, hearing aid compatible handsets, hearing aid telephone interconnect systems, and other products, address access for less than about 10% worldwide, for those that have a mild to moderate hearing loss. These products fail to meet the true needs of the population who need hearing access to telephones.
Existing hearing aid compatible or interconnect systems tend not to provide the power or the signal strength capture capability needed to directly couple to the hearing aid to ensure maximum telephone hearing access as is needed by millions of hearing aid users today. Either a person with a hearing disability cannot hear any sounds upon using one of these devices or they can hear something, but are having difficulties understanding the words being spoken on the phone. Some who have tried to use these types of devices tend to encounter what is known as “dead spots” i.e. when no sound transmission occurs, usually because of an inability to maintain capture of the signal because they do not hear sufficiently through the device.
It has been demonstrated to the Federal Communications Commission, including its Department of Engineering, that the performances of hearing aid compatible phones, volume controls and dual volume control handsets are the same. In effect their performances yield results that are equivalent to a slight raise of the sound volume. Such performance is inadequate, whether one uses a hearing aid or not. A consequence of these devices is that people with more than a mild to moderate hearing loss will not use a hearing aid compatible phone because these persons have, on the whole, not been able to adequately hear at any level using these products.
The upshot of these inadequacies is that a majority of the world's hearing impaired population still cannot access voice telecommunications. They have been denied access, convenience, and in many instances the life saving benefits of both wired and wireless phone usage in homes, offices, hotels, airports, restaurants, hospitals, jobs, pay phones, and more. The general unavailability of emergency phone access is particularly harsh for hearing impaired persons.
The scope of this lack of access is particularly evident because in the U.S. alone about 120 million public telephones are in use today. All of the pay phones that are currently deemed as hearing aid compatible or have volume controls only allow those individuals with mild to moderate hearing loss or those without hearing impairment access to these phones. Thus excluding a large number of persons from access to these phones.
Traditionally it has been normal practice to take the audio signal present in the environment and electronically inject it into the hearing aid of a person. This serves to circumvent an inherent problem associated with the poor reproductions of the acoustic audio signals as these are received by the hearing aid. For nearly 30 years, manufacturers have relied upon a device, known as the induction coil, to bypass the acoustic reproduction. For whatever reasons, be it poor design, or cost reduction, many of these devices fall short of delivering a quality audio signal to the hearing aid T-coil. Certainly, a convenient and simplified use of an effective hearing aid compatible handset has not been made available.
Various deficiencies are associated with prior art telephone to hearing aid type couplers. For example, many prior art products require a user to ascertain that switches and controls are set in an exact manner to perform one particular aspect of operation. These same controls must then be set up in a different fashion to achieve a different function. The result is the user tends to become frustrated and confused by the complexity of operating the product. Often many of the prior art devices require an assortment of cables and cords to be installed in exact manner. The possibility of a user mis-wiring the product is high and the user may not be able to figure out how to hook the device up properly.
When a user needs to wear a piece of headgear as described in the U.S. patent to Groppe the user feels foolish and silly. Many users would tend to be too embarrassed to use the device in both public and private settings. When a hard plastic coupler is involved, as is often the case, the product is uncomfortable and tends to be painful for the user to wear for a long time.
Ineffective performance is a particularly onerous deficiency in many of the prior art devices for enhancing telephone communication by hearing-impaired persons. These devices tend to under perform because of a variety of reasons such as a low sound pressure level, a lack of clarity, and the complexity imposed on the user to eliminate so-called “dead spots” in signal transmissions.
When a device as described in the aforementioned '821 patent is used, an air coil is employed. Such coil tends to waste available energy because it radiates the electromagnetic field in too many directions. As a result it is less efficient in coupling audio signals inductively to the hearing aid. An air coil also tends to have high impedance, typically of the order of about 90 to 120 ohms, and thus fails to create the desired electromagnetic field strength when driven by a typical semiconductor amplifier. This then imposes a greater battery load to properly power the air coil. An open air coil also tends to be large, typically in the range from 1″ long by about ¾″ wide.
FIGS. 14 and 15 depict the typical magnetic propagation of a prior invention as described in the aforementioned U.S. '821 patent. In this patent the magnetic lines of force tend to concentrate along the front, top, bottom and rear of the device. Very little magnetic lines of force 40 are devoted to going to the sides of the device 38.